A pixel is commonly misunderstood as solely a unit of area, like a tiny square on a screen. However, it's more accurate to consider a pixel as having both length and area. The length of a pixel refers to the distance between two adjacent pixel centers, influencing measurements like DPI (dots per inch). Pixel area is derived from this length, representing the visible square or rectangular region on the display. While often used interchangeably, distinguishing between pixel length and area is important for calculations involving display resolution, image scaling, and other graphical computations, ensuring accuracy and preventing potential confusion.
The Flea-Scope is a low-cost, open-source USB oscilloscope, logic analyzer, and arbitrary waveform generator. Designed with affordability and accessibility in mind, it utilizes a Cypress FX2LP microcontroller and features a minimalist design detailed in a comprehensive, publicly available PDF. The document covers hardware schematics, firmware, software, and usage instructions, enabling users to build, modify, and understand the device completely. The Flea-Scope aims to be a practical tool for hobbyists, students, and professionals seeking a basic, yet versatile electronic test instrument.
Commenters on Hacker News generally praised the Flea-Scope for its affordability and open-source nature, finding it a compelling option for hobbyists and those needing a basic tool. Several pointed out its limitations compared to professional equipment, particularly regarding bandwidth and sample rate. Some discussed potential improvements, including using a faster microcontroller and enhancing the software. The project's use of a Cypress FX2 chip was highlighted, with some expressing nostalgia for it. A few users shared personal experiences using similar DIY oscilloscopes, and others questioned the practicality of its low bandwidth for certain applications. The overall sentiment was positive, viewing the Flea-Scope as a valuable educational tool and a testament to what can be achieved with limited resources.
Cosmologists are exploring a new method to determine the universe's shape – whether it's flat, spherical, or saddle-shaped – by analyzing pairings of gravitational lenses. Traditional methods rely on the cosmic microwave background, but this new technique uses the subtle distortions of light from distant galaxies bent around massive foreground objects. By examining the statistical correlations in the shapes and orientations of these lensed images, researchers can glean information about the curvature of spacetime, potentially providing an independent confirmation of the currently favored flat universe model, or revealing a surprising deviation. This method offers a potential advantage by probing a different cosmic epoch than the CMB, and could help resolve tensions between existing measurements.
HN commenters discuss the challenges of measuring the universe's shape, questioning the article's clarity on the new method using gravitational waves. Several express skepticism about definitively determining a "shape" at all, given our limited observational vantage point. Some debate the practical implications of a closed universe, with some suggesting it doesn't preclude infinite size. Others highlight the mind-boggling concept of a potentially finite yet unbounded universe, comparing it to the surface of a sphere. A few commenters point out potential issues with relying on specific models or assumptions about the early universe. The discussion also touches upon the limitations of our current understanding of cosmology and the constant evolution of scientific theories.
NIST's Standard Reference Material (SRM) 2387, peanut butter, isn't for spreading on sandwiches. It serves as a calibration standard for laboratories analyzing food composition, ensuring accurate measurements of nutrients and contaminants like aflatoxins. This carefully blended and homogenized peanut butter provides a consistent benchmark, allowing labs to verify the accuracy of their equipment and methods, ultimately contributing to food safety and quality. The SRM ensures that different labs get comparable results when testing foods, promoting reliable and consistent data across the food industry.
Hacker News users discuss NIST's standard reference peanut butter (SRMs 2387 and 2388). Several commenters express amusement and mild surprise that such a standard exists, questioning its necessity. Some delve into the practical applications, highlighting its use for calibrating analytical instruments and ensuring consistency in food manufacturing and testing. A few commenters with experience in analytical chemistry explain the importance of reference materials, emphasizing the difficulty in creating homogenous samples like peanut butter. Others discuss the specific challenges of peanut butter analysis, like fat migration and particle size distribution. The rigorous testing procedures NIST uses, including multiple labs analyzing the same batch, are also mentioned. Finally, some commenters joke about the "dream job" of tasting peanut butter for NIST.
Summary of Comments ( 91 )
https://news.ycombinator.com/item?id=43769478
HN commenters largely agree with the article's premise that "pixel" can refer to both length and area. Some point out the context usually makes the meaning clear, similar to how "foot" can describe length or square footage. Others discuss the distinction between device pixels, CSS pixels, and other pixel variations, highlighting the importance of specifying which type of pixel is being discussed. A few commenters suggest the ambiguity arises from conflating the pixel count (area) with the physical size it represents (length). One commenter humorously likens using pixels for area to ordering a screen by the number of pixels instead of physical dimensions, imagining ordering a 1920x1080 inch screen instead of a standard size. Finally, some users offer alternative ways to express length in web design, like using relative units such as
remandem.The Hacker News post "Pixel is a unit of length and area" generated a moderate amount of discussion, with several commenters exploring nuances and offering differing perspectives on the article's premise.
One of the most compelling threads began with a user pointing out that the article overlooks the context of "device pixels" versus "CSS pixels". They explained that CSS pixels are abstract units designed for layout, while device pixels represent the physical hardware. This distinction is crucial for understanding how browsers handle scaling and resolution differences. Other users built upon this, elaborating on the roles of
devicePixelRatioand the complexities of achieving consistent rendering across diverse devices. This discussion highlighted the practical considerations that web developers face when working with pixels in a real-world environment.Another commenter raised the issue of square versus non-square pixels. They noted that while often assumed to be square, pixels can be rectangular, particularly in older or specialized display technologies. This observation added another layer to the discussion, reminding readers that the simple concept of a "pixel" can have subtle variations.
Several users expressed appreciation for the article's clarity in explaining a commonly misunderstood topic. They found the explanations of pixel density and the relationship between length and area in the context of pixels to be helpful.
Some users mentioned the challenges of working with different coordinate systems, highlighting the differences between screen coordinates and pixel coordinates. This tied back to the earlier discussion on device pixels versus CSS pixels, reinforcing the importance of context when discussing pixel measurements.
Finally, a few comments focused on the historical context of pixels, referencing early computer graphics and the evolution of display technology. This historical perspective provided an interesting backdrop to the more technical points raised in other comments.
Overall, the comments on the Hacker News post enriched the discussion around the concept of pixels, moving beyond the article's core points to explore practical implications, historical context, and the complexities of modern display technologies.